In filing cabinets, it is desirable that cabinets can be locked for security reasons, and when unlocked, that only one of the drawers can be pulled out at a time. That is, when one drawer is pulled out even partially, the other drawers should be locked against withdrawal, otherwise, costly and awkward excessive counterweights are required.
A wide variety of fairly complex interlock mechanisms have been proposed to accomplish both the security aspects of filing cabinets and to limit the opening of drawers to but one at a time. Examples of such prior art devices may be seen in the following U.S. Pat. Nos. 4,480,883; 4,429,930; 4,298,236; 3,900,236; 3,909,090; 3,888,558; 3,941,441; 4,355,851; 3,870,387; 4,425,013; 4,303,287; 3,404,929; and 2,240,067.
Because of the complexity of interlock mechanisms they are both costly and subject to failure. They can also be noisy. There is nothing more frustrating than a file drawer which won't open, or one which, when open, won't close properly, or when properly closed won't lock. Thus it is desirable to have a system of few parts with limited movement, and which can readily be replaced when broken or worn.